Liberty Vittert, visiting assistant professor in the Department of Mathematics and Statistics in Arts & Sciences

President Donald Trump has long focused on Chicago as a hotbed for American crime. This came up yet again on Oct. 8, when he said that he had directed the Justice Department to work with local officials in Chicago to stem violence in a city overwhelmed by its high rate of violent crime.

With 24.1 homicides per 100,000 people – more than four times the overall U.S. rate – Chicago certainly suffers from serious problems. But, as of a Sept. 25, St. Louis, my hometown, is called by the FBI the most dangerous city in America with over 6,461 violent crimes reported in the city limits in 2017. That’s an increase of more than 7 percent from the previous year.

St. Louis only ranks third for homicides in the U.S. by rate, but it’s the No. 1 most dangerous city. So by what metric does the government measure “most dangerous” – and why is Trump’s focus concentrated on Chicago and not St. Louis? As a statistician studying how people can manipulate numbers, particularly crime data, it is clear to me that the way crimes are currently counted in the U.S. can easily confuse and mislead.

Arts & Sciences

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